Not a good idea, generally speaking. It tends to interfere w/ the grower's ability to assess when the soil is dry.

Are you doing this for particular reason? Or 'cause you like how it looks? Houseplants don't need mulch, at least in the 10 yrs. I've grown my 150 or so plants, I've never heard or read so.

Also, from what I recall from family member's gardens who DID mulch, they did it w/ soft, porous materials, not rocks (which are inert). Soft mulching materials allow air circulation & are not heavy like stone.

My Dad used to mulch w/ old grass clippings, my Uncle used cocoa hulls on his garden beds & specialized & imported maple tree collection.

A top dressing is usually used for showing plants or for C&S. Used with a clay pot you can usually tell if a plant needs water by the color of your pot. I have most of my plants right now with a top dressing because I plan on showing them in two weeks time, but as soon as the show is over it is going to be removed. Some houseplants do benefit from a top dressing, but most of those are succulent like Sansevieria or the larger Crassulas. My pony tail palm and fockeas has a top dressing. It does make them look nicer and helps keep the moisture in the soil longer, but if you're prone to overwatering, this could be a problem. If you do use a top dressing, use a light brown with no dies, and a pebble size about 1/4 -1/3 in in diameter not smaller, and larger just looks funny on smaller plants.